July in Maryland Heights is the hottest month of the year. In July, the weather in Maryland Heights is typically hot. Average daily high temperature in July is about 31 degrees above zero. On average, Maryland Heights has 14 sunny, 11 rainy, 5 partly cloudy, and 1 cloudy day in July. The rains are usually heavy. July as well as January, February, March, and December is considered the most uncomfortable time to visit Maryland Heights.